This invention pertains, in general, to commercial and residential security and fire alarm systems and the like and, in particular to an arrangement for transmitting messages from alarm sensors to a control panel or the like.
One example of a residential or home alarm system is the Honeywell System 2000 Home Security System available from the Protection Services Division of Honeywell Inc. This system includes a control panel board to which a home security panel may be connected. The system can with an RF (radio frequency) receiver option support in addition up to seven hardwired loops and up to 94 RF transmitter points.
The RF transmitters may be coupled to alarm sensors such as magnetic door or window contacts or infrared motion detectors to send messages from the alarm sensors to the control panel board. Short range FM (frequency modulation) pulsed data cycle transmissions are utilized which in the United States are authorized by the Federal Communications Commission under Part 15 of the FCC regulations in a frequency range centered at approximately 315 mHz.
A typical alarm installation contains several RF transmitters. Each transmitter, if reporting an alarm condition, will transmit its message a plurality, e.g., six, times to increase the likelihood that the message will be received. There is, however, a possibility that in the event multiple transmitters transmit messages at approximately the same time, one alarm condition message may not be received due to overlap of the transmitted messages.